With increasing emphasis on water conservation, there is renewed interest in toilets and urinals designed to minimize the amount of water consumed in flushing and thus counteract increasing demands on water supplies as well as on wastewater disposal systems, both of which have tended to become overloaded with increasing populations.
Sanitation codes require all drain-connected items such as bathtubs, sinks, toilets and urinals, to provide an odor seal to contain gasses and odors which develop in the drain system, often developing positive sewer-pressure that can slightly exceed atmospheric pressure. Odor-sealing is conventionally performed by the well known P-trap or S-trap in which the seal is formed by a residual portion of the flushing water. As a marginal inherent disadvantage, P-traps and S-traps can become temporarily disfunctional due to “dry” failure in regions or periods of low humidity where infrequent usage trap could result in depletion of the residual liquid portion by evaporation to the extent that, in an eventual sealing failure, odors would escape.
In the category of urinals for males, “waterless” urinal facilities have been proposed and utilized to some extent in the past for their advantage of substantial savings of water usage and associated cost savings relative to water-flushed facilities. However, as a trade-off for these savings, the most viable approach, a “waterless” odor-trap cartridge for replaceable installation in a urinal bowl and utilizing an oily liquid sealant, still requires maintenance in the form of periodic inspection and replenishment of the oily liquid sealant, compared to relatively lower maintenance requirements of water-flushed urinals. Although not subject to evaporation and associated potential “dry” failure of P and S traps as described above, liquid sealant type waterless urinals generally require maintenance in the form of periodic inspection and replenishment of sealant loss, presumably in small droplets becoming detached from the sealant layer and swept down the drain with the wastewater flow at each usage and/or under surges of intensive usage or pressure hosing. Sealant replenishment is typically required in known waterless urinals after approximately 1,500 usages average, depending on frequency of usage.
In past time periods of plentiful water supply and non-overloaded wastewater disposal facilities, the conventional water-flushed type of urinal became generally accepted and widely used as the standard. More recently, marketplace demand driven by need for water conservation and the benefit of cost savings has resulted in ongoing replacement of pre-existing water-flushed urinals by waterless urinals as well as an increasing role in new construction. Waterless urinals that utilize oily liquid odor sealant have been approved under U.S. plumbing standards, e.g. the American National Standard for Plastic Urinal Fixtures, ANSI Z124.9-1993, particularly section 7.8: “Testing of waterless urinals”, and ASUE A112.14.14, and have gained increasing substantial acceptance throughout the world.
It is estimated that each of about 150,000 waterless urinal now in use saves an average of about 30,000 gallons of water per year per urinal compared to a flushed urinal, amounting to a saving of about 45 billion gallons of water annually. The financial savings include not only the initial treated water costs, but even more importantly the costs of sewage water treatment that run typically nearly three times the initial water cost, per gallon.
In many foreign countries, water-saving urinals in a different category, i.e. with moving parts, are allowed and are marketed and used in competition with waterless urinals that utilize liquid odor sealant. This category of urinals with moving parts claim as advantage the potential of being maintenance-free, however, due to awareness of potential risks of inherent unreliability and failure of moving parts due to debris, contamination and/or corrosion, U.S. plumbing and sanitation codes do not recognize or allow the category of odor traps that utilize flap technology, valves or other moving parts, whether of metal or flexible material.